Direct chill casting mold manifold apparatus

ABSTRACT

A direct chill casting mold assembly comprising a mold liner and a mold manifold. The mold manifold has at least two cooling medium chambers. A first chamber communicates with a source of cooling medium under pressure. Means are provided intermediate the first and second chambers for conducting the cooling medium from the first chamber to the second chamber. A substantial pressure drop is generally taken across the conducting means. Means are also provided which communicate with the second chamber for siphoning the cooling medium from the second chamber and applying it to a surface of the mold liner. The pressure loss between the two chambers assures uniform water distribution about the mold liner periphery.

United States Patent [1 1 Dore et al.

[ DIRECT CHILL CASTING MOLD MANIFOLD APPARATUS [75] Inventors: James E.Dore, Milford; Charles R.

MeNutt, l-lamden, both of Conn.

[73] Assignee: Olin Corporation, New Haven,

Conn.

[22] Filed: Aug. 13, 1971 [21] Appl. No.: 171,461

3,065,999 WugstuiT et ul 164/283 [451 July 31, 1973 PrimaryExaminerRobert D. Baldwin AttorneyRobert H. Bachman et al.

[57] ABSTRACT A direct chill casting mold assembly comprising a moldliner and a mold manifold. The mold manifold has at least two coolingmedium chambers. A first chamber communicates with a source of coolingmedium under pressure. Means are provided intermediate the first andsecond chambers for conducting the cooling medium from the first chamberto the second chamber. A substantial pressure drop is generally takenacross the conducting means. Means are also provided which communicatewith the second chamber for siphoning the cooling medium from the secondchamber and applying it to a surface of the mold liner. The pressureloss between the two chambers assures uniform water distribution aboutthe mold liner periphery.

40 Claims, 6 Drawing Figures Patented July 31, 1973 49,152

4 Sheets-Sheet 1 INVENTOR JAMES E DOPE f --l /g! 0104mm A. Mc/VUTTATTORNEY Patented July 31,1973 3,749,152

4 Sheets-Sheet 2 \J INVENTORS JAME .0095

CHARLE MC Nun ATTORNEY Patented July 31, 1973 4 Sheets-Sheet INVENTORJAMES E. DORE CHARLES R. MCNUTT ATTORNEY Patented July 31, 1973 ,4Sheets-Sheet 4 FE R32 853 Sn fi s: M6 EMEEMQ $32? 825% v 2 2 wm Q S Q QJAMES E DORE CHARLES R. Mc NUTT INVENTORS BY/ 2 fi ATTORNEY O Q Q DIRECTCHILL CASTING MOLD MANIFOLD APPARATUS BACKGROUND OF THE INVENTION Thisinvention relates to the field of direct chill casting of metals,particularly aluminum, aluminum-base alloys, copper and copper basealloys. The invention is directed to a chill casting mold assemblycomprising a mold liner arid mold manifold for applying a cooling mediumto a surface of the mold liner. The mold assembly in accordance withthis invention obtains a uniform distribution of coolant around theperiphery of the mold.

Uniform water distribution, particularly in extrusion ingot molds,contributes significantly to increased casting speeds, better ingotsurfaces, improved ingot internal structure and to reduced die wear andsuperior extruded surfaces.

The mold assembly in accordance with this invention also providesimproved productivity because its slim profile permits the nesting ofmolds in a honeycombed fashion, thereby providing a substantial savingsin space.

Single chamber mold manifold systems are nearly universally employedtoday. In a single chamber mold manifold system, cooling medium issupplied under pressure to a manifold chamber and is discharged from themanifold chamber through an annular slot and applied to a surface of themold liner. A single chamber manifold is subject to nonuniform waterdistribution even with the use of baffles or weirs. As one makes thesingle chamber design more compact, the uniformity of water distributiondecreases. This situation arises because the directionality of waterflow vectors is intensitied in smaller water chambers. As directionalityincreases, the nonuniformity of water delivery around the mold peripherybecomes greater.

Further, in single chamber manifold systems, the control of water flowand water distribution is determined by pressure drop across the annularwater discharge slot. The slot width is generally limited to 0.010 to0.015 inch and this small slot size makes alignment extremely criticaland thus precludes use of this type of mold assembly for casting ingotsof reasonably large cross section.

SUMMARY OF THE INVENTION In accordance with this invention, a directchill casting mold assembly has been developed which eliminates theaforenoted problems of the prior art assemblies. The mold assembly ofthis invention comprises a mold liner and a mold manifold having atleast two water chambers.

A first chamber communicates with a source of cooling medium underpressure which is generally water. Means are provided intermediate thefirst and second chambers for conducting the cooling medium from thefirst chamber to the second chamber. Generally speaking, a substantialpressure drop is taken across the conducting means. The conducting meanspreferably comprises a plurality of distribution holes. Means are alsoprovided which communicate with the second chamber for siphoning thecooling medium from the second chamber and applying it to a surface ofthe mold liner. The siphoning means generally comprises a leg which isformed between the mold liner and the manifold and communicates with thesecond chamber by means of siphon ports at one end and is provided withan annular cooling medium discharge slot at its other end.

Because the mold manifold system of the invention operates on theprinciple of the siphon, relatively large annular cooling mediumdischarge slots can be employed while maintaining uniform cooling mediumflow around the periphery of the mold. It has been found that with themold assembly of this invention, slight variations of the slot width dueto misalignment do not measurably affect the uniformity of waterdistribution.

.T he mold assembly of this invention overcomes flow directionalityproblems by utilizing at least two water chambers as opposed to thesingle chamber units of the prior art. In the double chamber design ofthis invention, the pressure loss between the two chambers assuresuniform water delivery around the mold periphery. Further, thedirectionality of the incoming water is hydraulically damped in the twochamber system.

Accordingly, it is a principal object of this invention to provide adirect chill casting mold assembly having improved uniformity ofdistribution of water about the mold periphery.

It is another object of this invention to provide a mold assembly asabove, wherein the mold manifold has at least two chambers.

It is a further object of this invention to provide a mold assembly asabove, wherein the cooling medium is applied to the mold liner by asiphoning action from the mold manifold.

It is a still further object of this invention to provide a moldassembly as above, having a slim profile, thereby permitting the nestingof mold assemblies in a compact fashion.

Other objects and advantages will become apparent from the followingdescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partial cross sectionalview of the mold assembly of this invention.

FIG. 2 is a partial top view of a direct chill casting table having aplurality of mold assemblies of this invention nested therein.

FIG. 3 is a perspective exploded view of the mold assembly of thisinvention.

FIG. 4 is a partial cross section view of the mold manifold.

FIG. 5 is a cross sectional view of a mold assembly in place and relatedcasting equipment during direct chill casting.

FIG. 6 is a graph illustrating the uniformity of cooling mediumdistribution about the periphery of the mold of this invention ascompared with a prior art assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawingsand especially to FIG. I, there is illustrated a typical direct chillcasting mold assembly I in accordance with this invention. The moldassembly I comprises a mold liner 2 and a mold manifold 3. The moldmanifold 3 supplies cooling medium, generally, water, which is appliedto a surface 4 of the mold liner 2. Water will be employed as thecooling medium in the remaining description, but the invention is notlimited thereto. The cooling medium forms no part of the invention andany desired cooling medium as are known in the art could be employed.

The mold liner 2 comprises a header portion 5 and a mold portion 6.Preferably, the mold liner 2 is an integral one piece casting, thoughother mold liner designs well known in the art could be employed.

A shoulder 7 is preferably provided at the top of the back wall 4 of theliner 2. This shoulder provides for self-centering of the liner 2 withinthe mold manifold 3 assuring concentricity of the liner and manifold.

The bottom of the mold liner is chamfered at 8 to define between themold liner 2 and the mold manifold 3 a water discharge slot 9. Byassuring the concentricity of theliner 2 and manifold 3, a uniform widthof the water discharge slot 9 is obtained.

As shown in FIGS. 2 and 3, the mold header 5 preferably has a polygonalshape such as the pentagonal one shown. This allows the mold assemblies1 to be nested in a honeycombed fashion in a casting table T and,thereby, obtain the closest packing and greatest density of moldassemblies for a given area. The pentagonal shape is particularlyadapted for use wherein the two rows of mold assemblies 1 are employedas shown in FIG. 2. However, if more than two rows were to be employed,hexagonal header portions 5 for at least the internal rows would providethe closest packing. The close center-to-center ingot spacing obtainablewith the inventive mold assemblies 1 is as much as twothirds less thanthat obtainable with typical prior art mold assemblies.

The mold manifold 3 of FIG. 1 contains at least two cooling mediumchambers 10 and 11. The first chamber 10 communicates with a source ofwater under pressure by means of inlet 12. Means 13 are providedintermediate the first 10 and second 11 chambers for conducting thewater from the first chamber into the second chamber.

This conducting means 13 generally comprises a plurality of distributionholes substantially equally spaced about an annular web W between thetwo chambers 10 and 11. The distribution holes 13 are generally sizedsuch that a substantial pressure drop occurs across them. The length todiameter ratio of the distribution holes is preferably greater than 2with the optimum at about 3. The pressure drop across the distributionholes 13 is preferably at least five times the pressure drop in anyother downstream portion of the mold manifold 3 system and, still morepreferably, the pressure drop between the two water chambers 10 and 1 lis from about 5 to 20 psi, with the optimum at about 7 psi.

Siphoning means 14 communicating with the second chamber 11 is providedfor siphoning the water from the second chamber and applying it to asurface 4 of the mold liner 2. Preferably, the siphoning means 14comprises a plurality of siphon ports 15 substantially at one end of asiphon leg 16 defined by the back surface 4 of the mold liner 2 and theinner surface 17 of the mold manifold 3. The siphon ports 15 aresubstantially equally spaced about the inside periphery 17 of the moldmanifold 3.

An annular ledge 18 or lip is provided as best shown in FIG. 4 about theinside surface 17 of the mold manifold 3 at the discharge end of thesiphon leg 16. The slot 9 defined by this lip 18 and the chamferedportion 8 of the mold liner 2 comprises the annular water discharge slot9.

The width of the annular water discharge slot 9 may be set as desiredand is generally at least 0.030 inch and, preferably, on the order ofabout 0.060 to 0.090 inch wide.

As aforenoted, a substantial pressure drop is provided across theconducting means 13 or distribution holes; however, a relativelyinsignificant pressure drop is obtained across the siphon ports 15 andthe cooling medium discharge slot 9, preferably, less than 1 psi withthe optimum at about 0.5 psi. This permits the size of the siphon ports15 and the discharge slot 9 to be relatively large as compared to knownassemblies.

Referring again to FIG. 3, the manifold 3 is preferably formed of acasting; however, it may be formed by any desirable techinque known inthe art, for example, as by welding pieces together to obtain thestructure shown. When the manifold 3 is formed preferably as in FIG. 3,the top 19 and bottom 20 surfaces are open in parts and contain slots 21or holes which communicate with the chambers 10 and 11.

The slots 21 are formed by virtue of casting practice and in order to beable to clean or otherwise maintain the manifold structure. The slots 21do not form a part of the instant invention and need not be present.However, when an open manifold is employed, referring to FIGS. 1 and 3,it is necessary to seal these slots 21 or openings by employing a gasket22 between the mold liner 2 and the upper surface 19 of the moldmanifold 3 and by employing a gasket 23 and cover plate 24 cov ering theopenings in the bottom surface 20 of the mold manifold 3.

Referring again to FIG. 4, it is seen that the first chamber 10is-considerably longer than it is wide, preferably, the length-to-widthratio of the first chamber is greater than 2 to l. The same applies forthe second chamber 11 with the second chamber having an even greaterlength-to-width ratio than the first chamber 10. Preferably, thelength-to-width ratio of the second chamber is greater than 3 to l withthe optimum at about I2 to 1. By employing such a design, it is possiblein accordance with this invention to obtain mold assemblies having veryslim profiles.

In practice, for an 8 inch diameter mold, it has been possible to employwidths in the first chamber 10 as narrow as five-eighths inch and widthsin the second chamber 11 as narrow as three-eighths inch and to provideoverall thickness from the inside mold wall 25 to the outside manifoldwall 26 of only l-3/ l 6 inch. These dimensions are exemplary of theslim profiles which can be obtained with the mold assembly I with thisinvention and are not meant to be limitive thereof, and may be varied asdesired.

The mold assembly 1 of this invention provides a favorable pressure dropratio between the pressure drop taken across the conducting means 13 ordistribution holes and the pressure drop taken across the siphon ports15 and the annular water discharge slot 9 and, thereby, assures uniformdistribution of water around the periphery of the mold.

The minimum practical water flow discharged from each mold is preferably0.6 gpm/inch of periphery of the water discharge slot (gpm gallon perminute). Thus, for an 8 inch diameter mold 1 having a 25 inch slot 9periphery, the lowest practical flow rate is somewhat less than 15 gpm.A continuous water curtain will be maintained at this low rate ofcoolant delivery.

The maximum flow rate is defined essentially by the quantity of waterneeded for casting and the head capacity of the pumps. Preferably, foraluminum and aluminum base alloys, the total water flow rate in gallonsper minute to weight rate of metal being cast in pounds per minute isfrom about 0.2 to 2.5 gallons per pound with the optimum volume at about0.5 gallons per pound. Reasonable casting practices will not normallyrequire more than 1 gallon per pound of metal being cast.

The conducting means 13 or distribution holes allow the water enteringthe second chamber 11 to be delivered uniformly around the periphery ofthe manifold 3. The primary purpose of the second chamber 11 is todissipate the velocity head of the water exiting from the distributionholes 13. By providing the long narrow flow path in the second chamber11, quiescent flow is obtained through the siphon ports 15.

The siphon ports 15 which are relatively large feed the water to thesiphon leg 16. The water flows down the siphon leg 16 and is applied tothe ingot through the discharge slot 9. Flow control is accomplished byregulating the amount of water delivered to the first chamber and thepressure drop across the conducting means 13 or distribution holes. Thesecond chamber 1 l and siphon leg 16 act as a barometric leg and remainfull of water at all times. By providing the water flow into the siphonleg 16, by the siphon principle the uniform water distribution achievedby the pressure drop between the two chambers 10 and 11 is retained.

The mold assembly 1 of this invention is particularly useful in thecasting of aluminum, aluminum base alloys, copper and copper basealloys, though its application is not limited to these metals andalloys. By virtue of the fact that the mold assemblies 1 of thisinvention can operate at relatively low water flows, they overcome asevere problem in prior art designs when casting stress sensitivealuminum alloys of the 2,000 and 7000 series. Such alloys are prone tocracking during direct chill casting, particularly as the transverseingot cross section increases.

As a general rule, stress sensitive aluminum alloy ingots with a minimumtransverse dimension of 14 inches or more cannot be cast consistantly inproduction with a high ingot recovery, namely, 95 percent or more unlesscooling water rates are on the order of 0.4 gallons per pound ofaluminum cast or less. Single chamber mold manifold units do not operatereliably at this low flow level.

The mold assemblies 1 of this invention on the other hand have shownthat operation at 0.4 gallons per pound of aluminum is entirely feasablyand, in fact, satisfactory performance prevails at rates as low as 0.2gallons per pound of aluminum cast. Consequently, the design of thisinvention provides improved ingot recoveries when used for castingstress sensitive alloys.

Referring again to FIG. 1, it has been found that preferably the ratioof the length of the first water chamber 10 to the diameter of the waterinlet 12 is greater than or equal to l to l with the optimum value at 2to 1. Further, it has been found that preferably the ratio of the widthof the second chamber 11 to the diameter of the distribution holes 13should be greater than 1-5: to l with the optimum value at about 3 to l.

The length of the mold portion 6 may be set as desired in accordancewith known practices in the art; however, long mold lengths increase thetendency for warpage of the mold liner 2 and promote the use pf highermolten metal heads in the mold which have an adverse effect on billetsurface quality.

In accordance with this invention, the mold length is preferably theminimum practical length necessary to provide adequate time for fillingand solidification of the molten metal in the mold at the start of adrop. The optimum mold length 6 has been determined to be 4-5: inches orless. A short mold length such as this allows for high speed castingwith excellent surface quality.

Referring to FIG. 5, there is shown a mold assembly 1 of this inventionduring the casting operation. The mold assembly 1 is set in a table Tsuch as that shown in FIG. 2 and the water inlet 12 is connected to asource of water under pressure.

The molten metal M is delivered to the mold by a novel nozzle 30 andconical flow distributing means 31 which is the subject of companion US.Pat. application Ser. No. 171,462, filed of even date herewith by PeterE. Sevier, assigned to the assignee of the instant invention.

The novel distribution mechanism comprises a nozzle 30 which isconnected to a source of molten aluminum such as a launder 32 at one endand at the other end is immersed in the molten aluminum Min the castingassembly 1. A conical distributor 31 is held under the nozzle 30 bymeans of a Marinite float 33. The nozzle protrudes through a hole 34 inthe Marinite float 33 with the diameter of the hole 34 being onlyslightly larger than the diameter of the nozzle 30. By virtue of thisrelationship the alignment between the conical distributor 31 and thenozzle 30 is readily maintained.

Further, the float 33 and cone 31 regulate the flow of aluminum into themold liner 2 since as the aluminum level in the mold rises carrying thefloat 33 with it the conical distributor 31 reduces the flow or entirelyshuts it ofi.

As shown in FIG. 5, the molten metal M solidifies about its outsidesurface 35 such that the outside surface is sufficiently solid tomaintain the integrity of the casting C after it has passed the end ofthe mold liner 2. As shown, the interior 36 of the casting is stillmolten when the casting has dropped below the end of the mold liner 2.

Casting is initially begun by employing a bottom block as is known inthe art which sits up within the mold liner 2 until the casting C hassufi'iciently solidified to begin the drop. The length of the casting isdictated only by the facilities, namely, the melting capacity and spaceavailable. As shown in FIG. 2, a plurality of castings may be pouredfrom a single melt by employing a cluster of mold assemblies 1 as shown.

The drop rate or casting rate is significantly improved by employing themold assemblies of this invention because of the improved efficiency ofthe cooling medium distribution.

FIG. 6 illustrates the improved uniformity of peripheral distribution ofwater around the mold assembly 1 of this invention over a wide range offlow rates as compared to a prior art single chamber mold assemblycommonly used in the field. Flow tests were run at water flows of 20, 30and 45 gpm.

The mold assemblies 1 of this invention produce a continuous watercurtain at 20 gpm and an extremely uniform water distribution. Bycontrast, the water distribution of the prior art mold was very poor.The flow pattern from this mold at 20 gpm and all other flow rates wasragged and discontinuous.

In FIG. 6, the solid lines represent the flow rates of water issuingfrom the water discharge slot 9 as a function of slot position aroundthe periphery of the mold. The dashed lines present similar data forprior art molds.

It is noted that at one point, no flow issued at all from the prior artmold. Neglecting this point, however, the variation in flow as afunction of position around the periphery prior art mold is about i 40percent. at 20 gpm, :2 75 percent at 30 gpm and i 100 percent at 45 gpm.This compares with a variation in water flow for unit slot length at allflow rates for the mold assemblies of this invention of less than i Ipercent.

These data point out the clear superiority of the mold assemblies I ofthis invention as compared to typical prior art single chamber manifoldmold assemblies.

The invention has been described with reference to cylindrical typemolds; however, it is also applicable to other mold shapes such as sheetor slab molds.

Molds for sheet or slab ingots and other noncylindrical shapes alsorequire uniform water distribution with the exception of the cornerswhere the cooling surface to volume ratio varies from the broad facesand end faces. Comer conditions are readily handled by blocking andreducing water flow. The problem in noncylindrical molds is to achieveuniform distribution of cooling medium at the broad faces and end facesof the mold. This problem can be solved by employing the novel moldmanifold siphon leg cooling means of this invention.

The mold manifold assembly 1 of this invention as applied tononcylindrical molds would have a cross section substantially the sameas that for a cylindrical mold as shown in FIG. 1, except the peripheryof the mold liner 2 would be noncylindrical and the manifold 3 wouldconform to the noncylindrical shape of the mold liner 2.

In the mold manifold assembly 1 shown in FIG. 1, the mold liner 2extends over only a portion of the length of the mold manifold 3. Thisis not meant to be limitive of the invention and the length of the moldliner 2 as compared to the mold manifold 3 may be set as desired bymerely providing the lip 18 at an appropriate position on the insidewall 17 of the mold manifold 3 to form the annular water discharge slot9.

It has been found that the cross sectional area of the inlet 12 shouldbe greater than or equal to the sum of the cross sectional areas of thedistribution holes 13 in order to assure proper and complete filling ofthe first chamber 10.

The materials employed in the various parts of the mold manifoldassembly of this invention are the same as those used in conventionaldirect chill casting mold assemblies.

The prior art single chamber mold manifold mold assemblies have beendescribed with reference to the use of an annular water discharge slotsince a similar means is preferred for use in accordance with thisinvention. However, sometimes, prior art mold assemblies employ aplurality of small diameter holes equally spaced about the periphery ofthe manifold in place of a discharge slot. When holes are used, holesize is also limited generally to a maximum diameter of about threethirtyseconds inch. I-Ioles of this size are very susceptable toplugging.

Length measurements as described above are measured in the direction ofcasting, or more specifically, metal travel through the mold portion 6.

It is to be understood that the invention is not limited to theillustrations described and shown herein, which are deemed to be merelyillustrative of the best modes of carrying out the invention, and whichare suitable of modification of form, size, arrangement of parts anddetails of operation. The invention rather is intended to encompass allsuch modifications which are within its spirit and scope as defined'bythe claims.

What is claimed is:

1. In a direct chill casting mold assembly comprising a mold liner andcooling means for applying a cooling medium to a surface of said moldliner, the improvement wherein said cooling means comprises:

a manifold having at least a first and a second chamber, said firstchamber communicating with a source of cooling medium under pressure;

means intermediate said first and second chambers for conducting saidcooling medium under pressure from said first chamber to said secondchamber, a substantial pressure drop being taken across said conductingmeans; and

means communicating with said second chamber for siphoning said coolingmedium from said second chamber and applying said cooling medium to saidsurface of said mold liner.

2. In an assembly as in claim 1, the improvement wherein said conductingmeans comprises an annular web having a plurality of distribution holestherein.

3. In an assembly as in claim 2, the improvement wherein said siphoningmeans comprises a siphon leg defined by the space between said moldliner and said manifold, with the discharge end of said siphon legterminating in an annular cooling medium discharge slot, said siphon legcommunicating with said second chamber by means of a plurality of siphonports.

4. In an assembly as in claim I, the improvement wherein said pressuredrop across said conducting means is from about 5 to 20 psi.

5. In an assembly as in claim 3, the improvement wherein thedistribution holes have a length to diameter ratio greater than 2 to l.v

6. In an assembly as in claim 5, the improvement wherein the pressuredrop taken across said siphon ports and said discharge slot is less than1 psi.

7. In an assembly as in claim 6, the improvement wherein the length towidth ratio of said first chamber is greater than 2 to l and the lengthto width ratio of said second chamber is greater than 3 to l.

8. In an assembly as in claim 7, the improvement wherein said source ofcooling medium communicates with said first chamber through a coolingmedium inlet and wherein the ratio of the length of the first chamber tothe diameter of the cooling medium inlet is greater than or equal to Ito l and, further, wherein the ratio of the width of the second chamberto the diameter of the distribution holes is greater than 14% to l.

9. In an assembly as in claim 8, the improvement wherein said mold linercomprises a mold portion and a header portion, and said header portionhas a polygonal shape.

10. In an assembly as in claim 8, the improvement wherein said coolingmedium discharge slot is defined by the gap between an annular lip aboutthe inside periphery of said manifold and a chamfered portion at thedischarge end of said mold liner.

11. In an assembly as in claim 9, the improvement wherein said headerportion has a pentagonal shape.

12. In an assembly as in claim 10, the improvement wherein said headerportion has a hexagonal shape.

13. In an assembly as in claim 9, the improvement wherein a shoulder isprovided about the outside periphery of said mold liner at theintersection of said mold portion and said header portion, whereby saidmold liner is self-centering within said manifold.

14. In an assembly as in claim 9, the improvement wherein the length ofsaid mold portion is 4% inches or less.

15. In an assembly as in claim 9, the improvement wherein said moldportion has a cylindrical shape.

16. In an assembly as in claim 9, the improvement wherein said moldportion has a noncylindrical shape.

17. A direct chill casting mold manifold for applying acooling medium toa surface of a mold comprising:

a first chamber communicating with a source of cooling medium underpressure; a second chamber, said second chamber having a length to widthratio greater than 3;

means intermediate said first and second chambers for conducting saidcooling medium under pressure from said first chamber to said secondchamber, a substantial pressure drop being taken across said conductingmeans; and

means communicating with said second chamber for siphoning said coolingmedium from said second chamber, said siphoning means being adapted toapply said cooling medium to said surface of said mold. i

18. A manifold as in claim 17 wherein said second chamber has a lengthto width ratio of 12 to l.

19. A manifold as in claim 17 wherein said conducting means comprises anannular web having a plurality of distribution holes therein.

20. A manifold as in claim 19 wherein said distribution holes have alength to diameter ratio greater than 2 to l.

21. A manifold as in claim 17 wherein said pressure drop across saidconducting means is from about to 20 psi.

22. A manifold as in claim 20 wherein the length to width ratio of saidfirst chamber is greater than 2 to I and the length to width ratio ofsaid second chamber is greater than 3 to 1.

23. A manifold as in claim 22 wherein said source of cooling mediumcommunicates with said first chamber through a cooling medium inlet andwherein the ratio of the length of the first chamber to the diameter ofthe cooling medium inlet is greater than or equal to l to I and,further, wherein the ratio of the width of the second chamber to thediameter of the distribution holes is greater than 1-95 to I.

24. A manifold as in claim 23 wherein an annular lip is provided aboutthe inside periphery of said manifold, said lip being adapted to formwith the discharge end of said mold an annular cooling medium dischargeslot.

25. In a direct chill casting table having a plurality of moldassemblies therein for casting a plurality of ingots from a single melt,each of said mold assemblies comprising a mold liner and cooling meansfor applying a cooling medium to a surface of said mold liner, theimprovement wherein said cooling means comprises:

a manifold having at least a first and second chamber,

said first chamber communicating with a source of 5 cooling medium underpressure;

means intermediate said first and second chambers for conducting saidcooling medium under pressure from said first chamber to second chamber,a substantial pressure drop being taken across said conducting means;and means communicating with said second chamber for siphoning saidcooling medium from said second chamber and applying said cooling mediumto said surface of said mold liner.

26. In a casting table as in claim 25, the improvement wherein saidconducting means comprises an annular web having a plurality ofdistribution holes therein.

27. In a casting table as in claim 26, the improvement wherein saidsiphoning means comprises-a siphon leg defined by the space between saidmold liner and said manifold, with the discharge end of said siphon legterminating in an annular cooling medium discharge slot, said siphon legcommunicating with said second chamber by means of a plurality of siphonports.

28. In a casting table as in claim 25, the improvement wherein saidpressure drop across said conducting means is from about 5 to 20 psi.

29. In a casting table as in claim 27, the improvement wherein thedistribution holes have a length to diameter ratio greater than 2.

30. In a casting table as in claim 29, the improvement wherein thepressure drop taken across said siphon ports and said discharge slot isless than I psi.

31. In a casting table as in claim 30, the improvement wherein thelength to width ratio of said first chamber is greater than 2 and thelength to width ratio of said second chamber is greater than 3.

32. In a casting table as in claim 31, the improvement wherein saidsource of cooling medium communicates with said first chamber through acooling medium inlet and wherein the ratio of the length of the firstchamber to the diameter of the cooling medium inlet is greater than orequal to l and, further, wherein the ratio of the width of the secondchamber to the diameter of the distribution holes is greater than l-r.

33. In a casting table as in claim 32, the improvement wherein said moldliner comprises a mold portion and a header portion, and said headerportion has a polygonal shape.

34. In a casting table as in claim 32, the improvement wherein saidcooling medium discharge slot .is defined by the gap between an annularlip about the'inside periphery of said manifold and a chamfered portionat the discharge end of said mold liner.

35. In a casting table as in claim 33, the improvement wherein saidheader portion has a pentagonal shape.

36. In a casting table as in claim 33, the improvement wherein saidheader portion has a hexagonal shape.

37. In a casting table as in claim 33, the improvement wherein ashoulder is provided about the outside periphery of said mold liner atthe intersection of said mold portion and said header portion, wherebysaid mold liner is self-centering within said manifold.

38. In a casting table as in claim 33, the improvement wherein thelength of said mold portion is 4- /5 inches or less.

39. In a casting table as in claim 33, the improvement wherein said moldportion has a cylindrical shape.

40. In a casting table as in claim 33, the improvement wherein said moldportion has a noncylindrical shape. 8 it i

1. In a direct chill casting mold assembly comprising a mold liner andcooling means for applying a cooling medium to a surface of said moldliner, the improvement wherein said cooling means comprises: a manifoldhaving at least a first and a second chamber, said first chambercommunicating with a source of cooling medium under pressure; meansintermediate said first and second chambers for conducting said coolingmedium under pressure from said first chamber to said second chamber, asubstantial pressure drop being taken across said conducting means; andmeans communicating with said second chamber for siphoning said coolingmedium from said second chamber and applying said cooling medium to saidsurface of said mold liner.
 2. In an assembly as in claim 1, theimprovement wherein said conducting means comprises an annular webhaving a plurality of distribution holes therein.
 3. In an assembly asin claim 2, the improvement wherein said siphoning means comprises asiphon leg defined by the space between said mold liner and saidmanifold, with the discharge end of said siphon leg terminating in anannular cooling medium discharge slot, said siphon leg communicatingwith said second chamber by means of a plurality of siphon ports.
 4. Inan assembly as in claim 1, the improvement wherein said pressure dropacross said conducting means is from about 5 to 20 psi.
 5. In anassembly as in claim 3, the improvement wherein the distribution holeshave a length to diameter ratio greater than 2 to
 1. 6. In an assemblyas in claim 5, the improvement wherein the pressure drop taken acrosssaid siphon ports and said discharge slot is less than 1 psi.
 7. In anassembly as in claim 6, the improvement wherein the length to widthratio of said first chamber is greater than 2 to 1 and the length towidth ratio of said second chamber is greater than 3 to
 1. 8. In anassembly as in claim 7, the improvement wherein said source of coolingmedium communicates with said first chamber through a cooling mediuminlet and wherein the ratio of the length of the first chamber to thediameter of the cooling medium inlet is greater than or equal to 1 to 1and, further, wherein the ratio of the width of the second chamber tothe diameter of the distribution holes is greater than 1- 1/2 to
 1. 9.In an assembly as in claim 8, the improvement wherein said mold linercomprises a mold portion and a header portion, and said header portionhas a polygonal shape.
 10. In an assembly as in claim 8, the improvementwherein said cooling medium discharge slot is defined by the gap betweenaN annular lip about the inside periphery of said manifold and achamfered portion at the discharge end of said mold liner.
 11. In anassembly as in claim 9, the improvement wherein said header portion hasa pentagonal shape.
 12. In an assembly as in claim 10, the improvementwherein said header portion has a hexagonal shape.
 13. In an assembly asin claim 9, the improvement wherein a shoulder is provided about theoutside periphery of said mold liner at the intersection of said moldportion and said header portion, whereby said mold liner isself-centering within said manifold.
 14. In an assembly as in claim 9,the improvement wherein the length of said mold portion is 4- 1/2 inchesor less.
 15. In an assembly as in claim 9, the improvement wherein saidmold portion has a cylindrical shape.
 16. In an assembly as in claim 9,the improvement wherein said mold portion has a noncylindrical shape.17. A direct chill casting mold manifold for applying a cooling mediumto a surface of a mold comprising: a first chamber communicating with asource of cooling medium under pressure; a second chamber, said secondchamber having a length to width ratio greater than 3; meansintermediate said first and second chambers for conducting said coolingmedium under pressure from said first chamber to said second chamber, asubstantial pressure drop being taken across said conducting means; andmeans communicating with said second chamber for siphoning said coolingmedium from said second chamber, said siphoning means being adapted toapply said cooling medium to said surface of said mold.
 18. A manifoldas in claim 17 wherein said second chamber has a length to width ratioof 12 to
 1. 19. A manifold as in claim 17 wherein said conducting meanscomprises an annular web having a plurality of distribution holestherein.
 20. A manifold as in claim 19 wherein said distribution holeshave a length to diameter ratio greater than 2 to
 1. 21. A manifold asin claim 17 wherein said pressure drop across said conducting means isfrom about 5 to 20 psi.
 22. A manifold as in claim 20 wherein the lengthto width ratio of said first chamber is greater than 2 to 1 and thelength to width ratio of said second chamber is greater than 3 to
 1. 23.A manifold as in claim 22 wherein said source of cooling mediumcommunicates with said first chamber through a cooling medium inlet andwherein the ratio of the length of the first chamber to the diameter ofthe cooling medium inlet is greater than or equal to 1 to 1 and,further, wherein the ratio of the width of the second chamber to thediameter of the distribution holes is greater than 1- 1/2 to
 1. 24. Amanifold as in claim 23 wherein an annular lip is provided about theinside periphery of said manifold, said lip being adapted to form withthe discharge end of said mold an annular cooling medium discharge slot.25. In a direct chill casting table having a plurality of moldassemblies therein for casting a plurality of ingots from a single melt,each of said mold assemblies comprising a mold liner and cooling meansfor applying a cooling medium to a surface of said mold liner, theimprovement wherein said cooling means comprises: a manifold having atleast a first and second chamber, said first chamber communicating witha source of cooling medium under pressure; means intermediate said firstand second chambers for conducting said cooling medium under pressurefrom said first chamber to second chamber, a substantial pressure dropbeing taken across said conducting means; and means communicating withsaid second chamber for siphoning said cooling medium from said secondchamber and applying said cooling medium to said surface of said moldliner.
 26. In a casting table as in claim 25, the improvement whereinsaid conducting means comprises an annular web having a plurality ofdistribution holes thereiN.
 27. In a casting table as in claim 26, theimprovement wherein said siphoning means comprises a siphon leg definedby the space between said mold liner and said manifold, with thedischarge end of said siphon leg terminating in an annular coolingmedium discharge slot, said siphon leg communicating with said secondchamber by means of a plurality of siphon ports.
 28. In a casting tableas in claim 25, the improvement wherein said pressure drop across saidconducting means is from about 5 to 20 psi.
 29. In a casting table as inclaim 27, the improvement wherein the distribution holes have a lengthto diameter ratio greater than
 2. 30. In a casting table as in claim 29,the improvement wherein the pressure drop taken across said siphon portsand said discharge slot is less than 1 psi.
 31. In a casting table as inclaim 30, the improvement wherein the length to width ratio of saidfirst chamber is greater than 2 and the length to width ratio of saidsecond chamber is greater than
 3. 32. In a casting table as in claim 31,the improvement wherein said source of cooling medium communicates withsaid first chamber through a cooling medium inlet and wherein the ratioof the length of the first chamber to the diameter of the cooling mediuminlet is greater than or equal to 1 and, further, wherein the ratio ofthe width of the second chamber to the diameter of the distributionholes is greater than 1- 1/2 .
 33. In a casting table as in claim 32,the improvement wherein said mold liner comprises a mold portion and aheader portion, and said header portion has a polygonal shape.
 34. In acasting table as in claim 32, the improvement wherein said coolingmedium discharge slot is defined by the gap between an annular lip aboutthe inside periphery of said manifold and a chamfered portion at thedischarge end of said mold liner.
 35. In a casting table as in claim 33,the improvement wherein said header portion has a pentagonal shape. 36.In a casting table as in claim 33, the improvement wherein said headerportion has a hexagonal shape.
 37. In a casting table as in claim 33,the improvement wherein a shoulder is provided about the outsideperiphery of said mold liner at the intersection of said mold portionand said header portion, whereby said mold liner is self-centeringwithin said manifold.
 38. In a casting table as in claim 33, theimprovement wherein the length of said mold portion is 4- 1/2 inches orless.
 39. In a casting table as in claim 33, the improvement whereinsaid mold portion has a cylindrical shape.
 40. In a casting table as inclaim 33, the improvement wherein said mold portion has a noncylindricalshape.